Numerous studies have demonstrated that extracts from higher plant species consist ofcompounds that have beneficial medicinal qualities, which have resulted in the improvementof current chemotherapeutic medicine available in the market. These medicinal plants haveability to produce many biologically active secondary metabolites. Cancer including morethan 100 different diseases which described by uncontrolled cellular growth, local tissueinvasion and distant metastasis.Thymus vulgaris, belonging to Lamiaceae plant familycommonly known as thyme. It is native to Southern Europe, where it is often cultivated as aculinary herb in Iran, Iraq, Turkey and etc. Locally knownâ€oeAvishan†in Iran and widelyemployed in folk medicine for its antibroncholitic, antispasmodic, anthelmintic, antitussiveand carminative properties. Iranian Thymus species have been, reported for theirantibacterial activities. It was discovered that the plants essential oil contains a powerfuldisinfectant called thymol that have ability in curing some diseases. Literature review shownthat there is insufficient scientific data available on T. vulgaris with respect to itsphytochemical and pharmacological properties. Thus, this study designed to prepare differentpolarity-based organic solvent extracts of T. vulgaris leaves and examine their cytotoxicproperties on some types of cancer cell lines. The plant material macerated with the hexane,ethanol,, methanol and water at 50 ºC. The samples were tested for possible anticanceractivity by using MTT assay on Human lung(A549) and prostate Cancer (IGR-CAP1) CellLines The results of these studies have shown that the ethanolic extract T. vulgaris exhibitedmost significant anti-proliferation activity among all the extracts with IC50 28± 1 Âμg/ml and36± 2 Âμg/ml on A549 and IGR-CAP1 cancer cell lines, respectively. This findingdemonstrate that the ethanolic extract of T. vulgaris has effective anticancer activity againsthuman lung cancer cells and Human prostate cancer cells and hence could be a potentialsource of chemotherapeutics for treatment of cancer.